LOW IF SELECTION METHOD FOR FM RADIO TUNER, AND FM RADIO TUNER USING THE IF

摘要

PROBLEM TO BE SOLVED: To provide a low IF selection method for FM radio tuners preventing influence of noises on a voice band, even if a low IF (intermediate frequency) is used.;SOLUTION: This FM radio tuner relates to a radio tuner which has at least a BPF 2 for decelerating signals other than a desired signal from signals received from an antenna 1, a mixing circuit 3 for performing conversion into an intermediate frequency by mixing an output signal from the BPF 2 and a signal from a local oscillator 4, the local oscillator 4 and a PLL circuit 5 for generating a signal for performing mixing with the output signal of the mixing circuit 3 to select a station of desired FM signals, an IF BPF 6 for extracting only a desired signal from intermediate frequency signals output from the mixing circuit 3, a limiter circuit 7 for making the amplitude of an FM signal constant, an FM detection circuit 8 for performing detection of the FM signal, and a stereo demodulation circuit 9 for demodulating the signal detected by the detection circuit 8, and the FM tuner uses a frequency near to a value even number times 38 kHz as the center frequency of its IF.;COPYRIGHT: (C)2006,JPO&NCIPI